1. Field of the Invention
The invention relates to a power sliding door. More particularly, the invention relates to a power drive mechanism mounted to a hinge member for opening and closing a power sliding door of an automotive vehicle.
2. Description of Related Art
In various types of automotive vehicles, including minivans, delivery vans, and the like, it has become common practice to provide a vehicle body with relatively large side openings that are located immediately behind front doors and which are opened and closed with a sliding side door. The sliding side door is typically mounted with upper and lower hinge members to horizontal tracks on the vehicle body for guided sliding movement between a closed position flush with the vehicle body, closing the side opening, and an open position located outward of and alongside the vehicle body rearward of the side opening. The sliding side door may be operated manually or with a power operated system to which the present invention is directed.
Examples of conventional power operated systems for automatically opening and closing the sliding side door are described in U.S. Pat. Nos. 6,481,783; 6,464,287; 6,435,600; 6,256,930; 6,079,767; 5,833,301; 5,644,869; 5,536,061; 5,434,487; 5,203,112; 5,168,666; and 4,612,729. Commonly assigned U.S. Pat. No. 6,435,600, which is hereby incorporated by reference as if fully set forth herein, discloses a power sliding door system for an automotive vehicle 10. A sliding door 36 is operated by a power drive mechanism 124 that is mounted to the door 36 and includes a drive motor 200 mounted within the door, a lower drive unit 204 having a rotatable pinion gear 208 mounted to a hinge member 120 fixed to the door 36, and a flexible driveshaft 202 coupling the drive motor 200 and pinion gear 208 for transmitting drive torque therebetween. The pinion gear 208 meshingly engages a rack 38 mounted along a floor 30 of a vehicle body 14 to open and close the door 36.
While the arrangement disclosed in U.S. Pat. No. 6,435,600 provides certain improvements in the pertinent art, several drawbacks have been noted. These drawbacks include, for example: (1) interference between drop glass in the door 36 and the drive motor 200; (2) excessive labor to install; (3) high drive torque losses in the curved flexible driveshaft 202 resulting in high manual efforts; (4) high cost of the flexible driveshaft 202 and lower drive unit 204 which includes a gear train consisting of bevel gears and ball bearings; and (5) excessive noise from the lower drive unit 204.
Another type of power sliding door system utilizing a rack 17 and a pinion gear 23 to effect the movement of a sliding side door 1 is disclosed in U.S. Pat. No. 4,612,729. This type of arrangement, however, requires considerable accommodating space and modifications to a vehicle body since a motor 18 and gear housing 19 are disposed within a floor of the vehicle body and move along the rack 17 together with the door 1.
U.S. Pat. No. 5,536,601 discloses another type of power sliding door system. The system utilizes a power drive mechanism 28 that is mounted to a sliding door 22 and extends through a side opening in the door 22. The drive mechanism 28 includes a reversible electric motor 62 that drives a friction wheel 38 which is spring biased to forcibly engage a guide track 40 located beneath a vehicle floor 14 and attached to a vehicle body 10. The friction wheel 38 rides along the guide track 40 to open and close the door 22 and additionally guides and stabilizes its sliding movement. Several drawbacks are associated with this arrangement, such as, the appearance of the door 22, and the cost, reliability and performance of the drive mechanism 28.
Various other types of power sliding door systems utilize a cable, chain, or belt to open and close the sliding side door. For example, U.S. Pat. No. 5,168,666 discloses a door drive device which includes a guide rail 2 in a vehicle body 1 defining a path along which a side door 3 moves. An endless belt 22 extends around first 17 and second 20 pulleys which are arranged at spaced positions within the vehicle body 1. A bracket 23 is provided for connecting a portion of the endless belt 22 to the side door 3 and a reversible electric motor 11 drives the first pulley 17 thereby moving the side door 3 between opened and closed positions. These types of power sliding door systems are complicated, include numerous parts, and require considerable accommodating space within a floor of the vehicle body 1 since the belt 22, first 17 and second 20 pulleys, and motor 11 are all disposed therein.
Consequently, it is desirable to provide a simple, inexpensive, quiet, compact, and easily installed power door drive system for opening and closing a power sliding door of an automotive vehicle.